Abstract: This study presents multi-physics three-dimensional finite element simulation of a fluid flow based self-excited micro energy harvester. This micro energy harvester is modeled inside a micro fluid channel to convert fluid flow energy into fluid oscillations. Investigations are carried out for the impact of low fluid flow velocity ranging 1-5 m sec-1, associated voltage generation by piezoelectric means and various mechanical analyses to enhance the performance and robust design considerations. The piezoelectric micro cantilever is attached to a D-shaped bluff body. An axial fluid flow and the D-shaped bluff body interaction generate Karman Vortex Street in the wake of the bluff-body. Vortex shedding causes an asymmetry in pressure distribution on the surface of the bluff body which results in time-dependent forces acting on the attached flexible micro cantilever. Due to structural vibrations induced by the uniform and steady fluid flow, periodic strains are generated in the piezoelectric cantilever which converts the strain energy into electrical charge. Finite Element Analysis Software namely COMSOL Multiphysics are used for the Harvester Model and simulation. In a 200x150x150 μm3 rectangular duct, at 5 m sec-1 fluid velocity, the 50x40x2 μm3 piezoelectric cantilever experienced 3088 Pa stress with cantilever tip displacement around 60 μm. A maximum voltage of 2.9 mV was recorded at 5 m sec-1 fluid velocity that is sufficient to drive an ultra-low-power rectifier circuit for a complete energy harvesting system. This study in detail describes the harvester device modeling and finite element analysis in COMSOL. Instead of using ambient parasitic vibration, this Energy Harvester Model directly utilize fluid flow energy to improve harvesting capability. The micro energy harvester self-charging capability makes it possible to develop untethered sensor nodes that do not require any wired connection or battery replacement or supplement batteries. Integration of fluid flow based micro energy harvester device for the autonomous sensor network such as automotive temperature and humidity sensor networks.
M.S. Bhuyan, B.Y. Majlis, M. Othman, Sawal H. Md. Ali and Shabiul Islam, 2013. Finite Element Analysis of a Fluid Flow Based Micro Energy Harvester. Research Journal of Applied Sciences, 8: 507-515.